Heat exchanger



FIG. 1 is a top front left perspective view of a heat exchanger, showing my new design;

FIG. 2 is a front elevation;

FIG. 3 is a rear elevation;

FIG. 4 is a left side elevation;

FIG. 5 is a right side elevation;

FIG. 6 is a top plan view;

FIG. 7 is a bottom plan view;

FIG. 8 is a cross section taken along line 8-8 of FIG. 2; and,

FIG. 9 is a cross section taken along line 9-9 of FIG. 2.

The broken lines in the drawings depict portions of the heat exchanger that form no part of the claimed design. 

CLAIM The ornamental design for a heat exchanger, as shown and described. 